The invention relates in general to explosive handling devices and in particular to a new and useful method and apparatus for the grinding of explosives, in which an explosive/water mixture is supplied to a mill, and the water is separated again from the ground-up explosive.
Explosives, such as octogen or hexogen, are available on the market in granulated form. For various production cases, however, they must be ground again. Thereby a defined, fine grain size distribution is achieved, which in the subsequent processing (e.g. pressing or pouring of an explosive charge from the explosive) has a decisive influence on the explosive density and hence the explosive power.
To illustrate problems which the present inventors have faced, an internal secret method of wet grinding of explosives, as practiced until now by the Applicant, will be explained more specifically with reference to FIG. 1 of the drawing, which schematically illustrates the grinding apparatus used by the applicant until now.
According to this internal method, inside a safety box (not shown), there is arranged, over a colloid or grinding mill 1 with a motor 2 and a hopper 3 on a stand 4, a charging hopper 5 which is closable with an inner cone 6 and into whose upper region a water conduit 7 leads. The explosive charge 8 is placed by hand in the charging hopper 5 closed with an inner cone 6, the mill 1 is flushed with water via a conduit (not shown). The inner cone 6 is raised, and then the explosive charge 8 is flushed with water from line 7 into the mill 1, whereupon the explosive/water mixture is ground in mill 1. The ground explosive is then conveyed to a suction filter 9, to separate the water from the explosive again. The grinding process is set in motion and supervised from outside the safety box.
In this plant-internal method the ratio of water to explosive in the mixture supplied to the mill varies considerably during the grinding of the explosives due to the flushing-in process. In particular, explosive may accumulate at the inlet of the mill 1.
This leads to problems of safety as well as of grinding. In the wet grinding of explosive, in fact, the explosive/water mixture supplied to the mill 1 must, for safety reasons, not fall below a certain ratio of water to explosive. For octogen or hexogen the lower limit of this ratio is about 3:1. On the other hand, too high a ratio of water to explosive in the mixture, that is for instance a ratio of 6:1, leads to a reduced grinding output. Through the considerable variation of the ratio of water to explosive in the mixture supplied to the mill, the 3:1 ratio may therefore either easily drop off below the safe ratio, or through too high a ratio the grinding output may be reduced. Moreover, the variation of the ratio of water to explosive in the mixture supplied to the mill, that is, an irregular mill throughput, diminishes the quality of the ground product through respective fluctuations of the grain size distribution.
Furthermore, the explosive charge 8 may contain foreign matter, in particular metal particles, which damage the mill or even trigger an incident.